Roll doctor apparatus

ABSTRACT

Apparatus for doctoring a roll for example in a paper-making machine, comprising a flexible doctor blade carried by a flexible support which extends into a rigid cylindrical carrier tube through a longitudinal opening defined by portions of the tube which are formed to provide pivot means for the support, two inflatable tubes which are interposed between the support and the carrier tube inside the latter for pivoting the support to cause the doctor blade to engage with or disengage from the roll and which locate the support relative to the carrier tube, and a guard plate carried by the support and arranged to direct material removed from the roll by the blade away from the opening in the carrier tube.

United States Patent Winterburn et al.

ROLL DOCTOR APPARATUS Inventors: Charles Barry Winterburn,

Hawkshaw Bury; Thomas Scholes, Ramsbottom, near Bury, both of England Joseph Winterhurn Limited, Bury, England Filed: Jan. 1, 1973 Appl. No.: 320,257

Assignee:

Foreign Application Priority Data Jan. 1, 1972 Great Britain 6/72 US. Cl l5/256.5l, 34/120, 100/174 Int. Cl D2lg 3/02, D21g 3/04 Field of Search 15/256.5l, 256.5; 34/110-121; 100/174; 118/126, 261, 256; 432/2, 75; 162/281, 282, 306; 68/270 References Cited UNITED STATES PATENTS 7/1973 Winterburn et al. l5/256.51

[451 Apr. 16, 1974 2,914,788 12/1959 Smith et a1 l5/256.51 3,407,428 10/1968 Galassi l5/256.51 3,611,471 10/1971 Meskanen et a1 15/256.51 3,327,341 6/1967 Kuehn 15/256.51

Primary Examiner-Leon G. Machlin. Attorney, Agent, or Firm.Spencer & Kay

[ 5 7] ABSTRACT Apparatus for doctoring a roll for example in a papermaking machine, comprising a flexible doctor blade carried by a flexible support which extends into a rigid cylindrical carrier tube through a longitudinal opening defined by portions of the tube which are formed to provide pivot means for the support, two inflatable tubes which are interposed between the support and the carrier tube inside the latter for pivoting-the support to cause the doctor blade to engage with or disengage from the roll and which locate the support relative to the carrier tube, and a guard plate carried by the support and arranged to direct material removed from the roll by the blade away from the opening in the carrier tube.

8 Claims, 3 Drawing Figures PATENTEUAPR \6 I974 SHEET 3 OF 3 Ed I\ CICJS ROLL DOCTOR APPARATUS BACKGROUND OF THE INVENTION This invention relates to a roll doctor apparatus for use with a roll in, for example, a paper making, bleaching dyeing or printing machine.

The invention is particularly applicable to an apparatus for doctoring the drying roll of a paper making machine and will be described in relation thereto, but it is to be understood that there is no limitation in this regard.

There are three important requirements of a roll doctor apparatus and these are as follows:

1. the apparatus should be capable of allowing for the camber of a long roll while providing substantially uniform pressure on the roll by the doctor blade along the length of the roll.

2. if pulp or other material removed from the roll by the doctor blade passes the latter, it must be prevented from impairing the proper operation of the apparatus and/or accumulating in such a position that it will ultimately drop off on to the web being acted upon by the roll.

3. it should be possible to lift the doctor blade off the roll when the machine is idleor for maintenance and replacement purposes.

It is an object of the present invention to provide a roll doctor apparatus which fulfils these requirements and which is of a comparatively simple and inexpensive construction.

SUMMARY OF THE INVENTION According to the invention we provide a roll doctor apparatus comprising a carrier which comprises a rigid cylindrical tube having a longitudinally extending opening formed in the wall thereof; a flexible support (as herein defined) which extends through the said opening and has portions thereof disposed respectively outside and inside the carrier, the support being pivotable relative to the carrier about anaxis extending longitudinally of the latter; a flexible doctor blade (as herein defined) mounted on the portion of the support outside the carrier; two tubes which are disposed inside the carrier andare interposed between the latter and opposite sides of the portion of the support inside the carrier, these tubes being expansible by the introduction of fluid into them so as to pivot the support relative to the carrier about said axis and cause the doctor blade to engage the roll and to lift from the roll, and being arranged to locate the support against inwards and outwards movement relative to the carrier; and a guard which is carried by the portion of the support outside the carrier and isarranged to extend in a direction away from the doctor blade and above the opening in the carrier to direct material removed from the roll away from said opening.

In this arrangement since the expansible tubes and the portion of the doctor blade support engaged thereby are enclosed by the carrier and a guard is provided to direct away from the opening in the latter through which the support extends, pulp or other material removed from the roll by the blade, no pulp or other material can enter the carrier through the opening and accumulate between the support and the expansible tubes. The guard will be made such that there is no tendency for any pulp or other material to hang on to it. The expansible tubes are protected by the carrier against puncturing, for example when the apparatus is being cleared of pulp or other material by means of a spiked rod or stick.

Furthermore, the apparatus is simpler and hence less expensive to manufacture than previously proposed forms of roll doctor apparatus. In this regard the carrier simply comprises a cylindrical tube formed with a longitudinally extending opening through which the doctor blade support extends, so that it can be produced in one piece without the necessity for securing together a number of component parts as in previously proposed forms of roll doctor apparatus. In addition by arranging the expansible tubes so that they act to locate the support against inwards and outwards movement relative to the carrier, additional means do not have to be specially provided for this purpose as in previous forms of roll doctor apparatus. The provision of two expansible tubes enables the doctor blade to be positively lifted from the roll as well as engaged with it.

When we say that the doctor blade and its support are flexible we mean that they are arranged so that the blade can engage the roll over the whole length thereof when the blade is urged into engagement with the roll by the relevant one of the expansible tubes. The blade will be in one piece .and such that it can flex about axes transverse to its length. The support may be continuous along the length of the roll and of sufficient flexibility about axes transverse to its length to enable the blade to engage the roll throughout the length of the latter but preferably it comprises a number of sections arranged side-by-side.

The opposed portions of the wall of the carrier which define the opening therein are preferably formed to constitute pivot means for the support. This further en hances the simplicity of the apparatus since the pivot means for the support are formed integrally with the carrier and therefore separate pivot means do not have to be specially provided as in previously proposed forms of roll doctor apparatus. In a specific embodiment the said portions of the wall of the carrier are formed so that the opening tapers from the interior to the exterior of the carrier, the narrow part of the opening being of a width substantially equal to the thickness of the portion of the support disposed therein whereby the support is pivotable about an axis extending along the narrow part of the opening.

Preferably the portion of the support inside the carrier is disposed in a radial plane of the latter and is provided with a cylindrical part which is concentric with the carrier, the two expansible tubes being each of partannular form in cross section and being interposed between diametrically opposed parts of the internal surface of the carrier and opposed parts of the external surface of the cylindrical part of the support so that when the tubes are expanded, they fill the majority of the annular space between the internal surface of the carrier and the external surface of the cylindrical part of the support thereby to locate the support against radial inwards and outwards movement relative to the carrier.

Preferably the guard comprises a plate having a curved portion which extends rearwardly in a direction away from the blade and around part of the circumference of the carrier in spaced relationship with the latter.

tion extending rearwardly from said part of the support in a direction away from the blade and being disposed in a plane parallel to said tangent .of the carrier, the curved portion "of the plate extending rearwardly from said flat portion.

7 BRIEF DESCRIPTION OF THE DRAWINGS The invention will now-be described in detail by way of example with reference to the accompanying drawings, in which:

FIG. l-isa vertical section through one form of roll doctor apparatus embodying the invention,

7 FIG. 2.= is aside elevation of the apparatus, and

I FIG. 3 isa view in the direction of arrow Ain FIG.

2, partly cut away.

DESCRIPTION OF THE PREFERRED EMBODIMENT The roll doctor apparatus illustrated in the drawings is arranged to doctor a roll 1, for example the drying roll .of a paper making machine in which event the roll acts upon a web of paper passing beneath it and the apparatus acts to remove pulp from the roll. The apparatus basically comprises a carrier.2 for a support 3 mounting a doctor-.bladex4. The carrier 2 comprises a cylindricaimetal rube 5, for example of steel, which is supported by mountings at its ends on afixed support platform 6. Each mounting comprises a -U-clamp 7 which'embraces the relevant end of the carrier tube 5 and the ends of which pass through the apertures in the support platform 6 and are screw threaded to receive nuts 8. A saddle 9, for example of metal, is interposed between the underside of each endof the carrier tube 5 and the support platform 6-andwhen the nuts 8 of the two U-clamps are tightened up the carrier tube is firmly clamped against the saddles. Adjustment-and removal of the carrier tube are permitted simply by releasing the nuts 8.,

The wall of the carrier tube 5 is formed with a longitudinally extending opening 10. The portions 11 of the wall of the tube which define the opening are formed so that the'latter tapers from the interior to the exterior of the. carrier, the support 3 extending through this opening and the narrow outer part of the latter being of a width substantially equal to the thickness of the portion of the support inside the opening whereby the support is pivotable relative to the carrier about an axis extending along the narrow part of the opening 10.

The support 3 has a portioninside the carrier tube 5 ,andthis portion is disposed in a radial plane of the latter and formed with .a cylindrical part 12 which is concentric with the carrier. Interposed between diametrically opposite parts of the internal surface of the carrier tube 5 and opposed parts of the external surface of the external surface of the cylindrical part 12 of the support are two inflatable tubes 13 and 14 each of partannular form in cross section. The tubes are closed at their ends by end plates 15 which are secured in the open ends of the carrier tube 5, these end plates sealing the ends ofthe inflatable tubes and the ends of the carrier tube in air-tight fashion. The end plate 15 at one end of the carrier tube is provided with two connections 16 which communicate respectively with the two inflatable tubes and are adapted to have air lines connected to them. These air lines are connected to a source of compressed air and incorporate valves operable to control the air pressure in the tubes.

The support 3 has a portion outside the carrier 2 and this portion is cranked. so that the outer part 17 thereof which carries the doctor blade 4 is disposed in a plane parallel to a tangent of thecarrier tube 5. Secured to this part 17 by means of rivets 18 is a guard plate 19 which has a flat portion 20 extending rearwardly from said part 17 in a direction away from the blade 4, and a curved portion 21 which extends rearwardly from the flat portion 20 and around part of the circumference of the carrier tube in spaced relationship therewith. The flat portion 20 of the guard plate 19, together with an appropriately shaped portion 22 of the support 3 defines a slot which receives the doctor blade 4. The base of the slot provides an abutment for the edge of the doctor blade remote from the edge which engagesthe roll 1, and the blade is provided with a series of spring clips 23 which removably hold the blade in position in the slot.

The doctor blade 4 is urged into engagement with the surface of the roll 1 by introducing compressed air into the tubes 13 and 14 with a greater pressure in the tube 14 than in the tube '13 so that the tube 14 expands to a greater extent and pivots the support 3 in an anticlockwise direction relative to the carrier tube 5 about the pivot means formed by the portions 1 1 of the latter. The tube 13 merely acts as a steady when the blade is being forced into engagement with the roll 1. The support 3 must be sufficiently flexible for the blade to be able to be engaged with the roll over the whole length of the latter and for this purpose the support comprises a'number of levers 24 arranged side-by-side as shown in FIG. 3. The blade 4 is formed in one piece and is flexible about axes transverse to its length. 7

With the roll 1 rotating in the direction of arrow X pulp scraped off the roll by the doctor blade 4 passes over the upper surface of the guard plate 19 and drops off the latter at the rear of the carrier 2. No material can accumulate on the portion of the support 3 outside the carrier or enter the carrier through the opening 10 therein and accumulate between the support and the inflatable tubes 13 and 14.

By introducing a greater air pressure into the tube 13 than into the tube 14 the support 3 can be pivoted in a clockwise direction to lift the doctor blade 4 from the roll 1.

The support 3 need not be cranked as described and illustrated in the drawings. It may be cranked in the opposite direction or it may be flat.

The support platform 6 and the mountings 7, 8 and 9 may be omitted and the carrier 2 connected to an oscillating unit which is arranged to oscillate the carrier axially thereby to reciprocate the doctor blade longitudinally of the roll 1 when it is in contact with the latter.

We claim: 1. In combination with a roll, a roll doctor apparatus comprising a. a carrier which comprises a rigid cylindrical tube having a longitudinally extending opening formed in the wall thereof;

b. a flexible support which extends through the said openingand has portions thereof disposed respectively outside and inside the carrier, the support being arranged for pivoting relative to the carrier about an axis extending longitudinally of the latter;

0. a flexible doctor blade mounted on the portion of the support outside the carrier;

. two expansible tubes which are disposed inside the carrier and are interposed between the latter and opposite sides of the portion of the support inside the carrier, the tubes being arranged to locate the support against inwards and outwards movement relative to the carrier; I

e. means for introducingfluid into the expansible tubes so as to pivot the support relative to the carrier about said axis and cause the doctor blade to engage the roll or to lift from the roll; and

f. a guard which is carried by the portion of the support outside the carrier and is arranged to extend in a direction away from the doctor blade and above the opening in the carrier to direct material removed from the roll away from said opening.

2. A roll doctor apparatus as claimed in claim 1 wherein the support comprises a number of sections arranged side-by-side and the blade is in one piece and flexible about axes transverse to its length.-

3. A roll doctor apparatus as claimed in claim 1 wherein the opposed portions of the wall of the carrier which define the opening therein are formed to constitute pivot means for the support.

4. A roll doctor apparatus as claimed in claim 3 wherein the portions of the wall of the carrier which define the opening therein are formed so that the opening tapers from the interior to the exterior of the carrier, the narrow part of the opening being of a width substantially equal to the thickness of the portion of the support disposed therein whereby the support is pivotable about an axis extending along the narrow part of the opening.

5. A roll doctor apparatus as claimed in claim 1 wherein the portion of the support inside the carrier is disposed in a radial plane of the latter and is provided with a cylindrical part which is concentric with the carrier, the two expansible tubes being each of partannular form in cross section and being interposed between diametrically opposed parts of the internal surface of the carrier and opposed parts of the external surface of the cylindrical part of the support so that, when the tubes are expanded, they fill the majority of the annular space between the internal surface of the carrier and the external surface of the cylindrical part of the support thereby to locate the support against radial inwards and outwards movement relative to the carrier.

6. A roll doctor apparatus as claimed in claim 1 wherein the guard comprises a plate having a curved portion which extends rearwardly in a direction away from the blade and around part of the circumference of the carrier in spaced relationship with the latter.

7. A roll doctor apparatus as claimed in claim 1 wherein the portion of the support outside the carrier is cranked so that the outer part thereof carrying the doctor blade is disposed in a plane parallel to a tangent of the carrier.

8. A roll doctor apparatus as claim in claim 7 wherein the guard plate comprises a flat portion which is con nected to the part of the support carrying the doctor blade, said flat portion extending rearwardly from said part of the support in a direction away from the blade and being disposed in a plane parallel to said tangent of the carrier, and a curved portion which extends rearwardly from said flat portion and around part of the circumference of the carrier in spaced relationship with the latter. 

1. In combination with a roll, a roll doctor apparatus comprising a. a carrier which comprises a rigid cylindrical tube having a longitudinally extending opening formed in the wall thereof; b. a flexible support which extends through the said opening and has portions thereof disposed respectively outside and inside the carrier, the support being arranged for pivoting relative to the carrier about an axis extending longitudinally of the latter; c. a flexible doctor blade mounted on the portion of the support outside the carrier; d. two expansible tubes which are disposed inside the carrier and are interposed between the latter and opposite sides of the portion of the support inside the carrier, the tubes being arranged to locate the support against inwards and outwards movement relative to the carrier; e. means for introducing fluid into the expansible tubes so as to pivot the support relative to the carrier about said axis and cause the doctor blade to engage the roll or to lift from the roll; and f. a guard which is carried by the portion of the support outside the carrier and is arranged to extend in a direction away from the doctor blade and above the opening in the carrier to direct material removed from the roll away from said opening.
 2. A roll doctor apparatus as claimed in claim 1 wherein the support comprises a number of sections arranged side-by-side and the blade is in one piece and flexible about axes transverse to its length.
 3. A roll doctor apparatus as claimed in claim 1 wHerein the opposed portions of the wall of the carrier which define the opening therein are formed to constitute pivot means for the support.
 4. A roll doctor apparatus as claimed in claim 3 wherein the portions of the wall of the carrier which define the opening therein are formed so that the opening tapers from the interior to the exterior of the carrier, the narrow part of the opening being of a width substantially equal to the thickness of the portion of the support disposed therein whereby the support is pivotable about an axis extending along the narrow part of the opening.
 5. A roll doctor apparatus as claimed in claim 1 wherein the portion of the support inside the carrier is disposed in a radial plane of the latter and is provided with a cylindrical part which is concentric with the carrier, the two expansible tubes being each of part-annular form in cross section and being interposed between diametrically opposed parts of the internal surface of the carrier and opposed parts of the external surface of the cylindrical part of the support so that, when the tubes are expanded, they fill the majority of the annular space between the internal surface of the carrier and the external surface of the cylindrical part of the support thereby to locate the support against radial inwards and outwards movement relative to the carrier.
 6. A roll doctor apparatus as claimed in claim 1 wherein the guard comprises a plate having a curved portion which extends rearwardly in a direction away from the blade and around part of the circumference of the carrier in spaced relationship with the latter.
 7. A roll doctor apparatus as claimed in claim 1 wherein the portion of the support outside the carrier is cranked so that the outer part thereof carrying the doctor blade is disposed in a plane parallel to a tangent of the carrier.
 8. A roll doctor apparatus as claim in claim 7 wherein the guard plate comprises a flat portion which is connected to the part of the support carrying the doctor blade, said flat portion extending rearwardly from said part of the support in a direction away from the blade and being disposed in a plane parallel to said tangent of the carrier, and a curved portion which extends rearwardly from said flat portion and around part of the circumference of the carrier in spaced relationship with the latter. 